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PostPosted: Mar 29th, '18, 22:03 
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Seriously, this cant be healthy.
Seriously, this cant be healthy.
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Is there a way to check the capacity of a 10Ah Lithium battery (pack) to see if it really is 10Ah?

I have a clamp meter.

They are 36v eBike battery packs, and normally have a load of up to 250 watts.

I've bought so many torches and things that come with a claimed 3400mAh battery only to find they weigh half as much as a panasonic battery of similar type. They also (obviously) dont last very long.

I heard tale of a portable power pack that had 3 batteries instead of six, and a sandbag where the other three should have been.

Oh well.

I'm sure corruption, dishonesty, and poor service will be a distant memory any minute now :dontknow:

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PostPosted: Mar 30th, '18, 06:02 
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Some battery chargers for Li batteries have a discharge function on them as well, which can be used to measure capacity. They are a few tens of dolalrs to buy.

Otherwise just measure current and voltage until the voltage starts to drop away (but don't let it go too far), and time it to work out capacity.

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PostPosted: Apr 1st, '18, 18:15 
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Seriously, this cant be healthy.
Seriously, this cant be healthy.
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OK thanks Gunagulla.

I found this...
https://www.ebay.com/itm/Coulometer-Bat ... Swu4BV3GR4

that claims "2. The principle of cumulative charge calculation using coulomb way to calculate capacity of battery, accuracy is very high!"

and this...
https://www.ebay.com/itm/DC8-80V-50A-Ba ... 0005.m1851

That looks like it uses a voltage regulator or similar (as a dump load maybe????)


If that first one would do the job, and not drain the battery pack in the process, it would be better because I could leave it connected as a fuel gauge.

Any chance you could have a peek at them and tell me what you think?

Or anyone else? I realise asking for help like this is always a pain, but I'd really like to know if these are the real deal as they are costing me nearly $700 in total.

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PostPosted: Apr 1st, '18, 18:42 
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For those prices, I'd expect them to be junk... cheap electronics from HK... no thanks!

In any case, you still have to discharge and recharge it if you are going to count Coulombs.

You don't have to fully discharge the battery to determine its approximate capacity anyway. Discharge it by 8AH and if the voltage hasn't collapsed, there's a good chance it is close to 10AH.

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My small AP system: http://backyardaquaponics.com/forum/viewtopic.php?f=18&t=16345
Larger 2nd system: http://www.backyardaquaponics.com/forum/viewtopic.php?f=18&t=24153
Solar powered Gunagulla Organic Garden
Fruit +Loomberah Wx
http://gunagulla.com


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PostPosted: Apr 2nd, '18, 10:12 
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Seriously, this cant be healthy.
Seriously, this cant be healthy.
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Joined: Mar 26th, '10, 20:46
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Location: South Australia
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Hmmm.Ok.

I dont want to spend too much because I'll defeat the purpose.

I've probably got $600 worth of battery regardless.

Maybe I'll just tell the seller I tested them and they didnt do very well and see how they react :)

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My skills include being able to move slowly forward in time, and if I really concentrate, I can sometimes tell what I'm thinking.


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